Fuel nozzle assembly for high fuel/air ratio and reduced combustion dynamics

Abstract

Fuel nozzle assemblies are provided. For example, a fuel nozzle assembly for a combustor system comprises a fuel nozzle having a pilot swirler and an outlet defined in an outlet end, as well as a main mixer attached to the outlet end and extending about the outlet. A total combustor airflow through the combustor system comprises a pilot swirler airflow that is greater than about 14% and a main mixer airflow that is less than about 50% of the total combustor airflow. In further embodiments, the fuel nozzle also comprises main and pilot fuel injectors that each are configured to receive a portion of a fuel flow to the fuel nozzle. The fuel nozzle provides less than about 80% of the fuel flow to the main fuel injector at a high power operating condition of a gas turbine engine in which the fuel nozzle assembly is installed.

What is claimed is: 
     
       1. A fuel nozzle assembly for a combustor system, comprising:
 a fuel nozzle having: 
 a pilot swirler defining a pilot air inlet for an ingress of a pilot swirler airflow, 
 a pilot splitter disposed within the pilot swirler that separates the pilot swirler airflow into two separate airflows, 
 a main fuel circuit for supplying fuel to a main fuel injector, 
 a pilot fuel injector, 
 an outer boundary wall circumferentially surrounding the pilot splitter, an aft end of the outer boundary wall including a heat shield directly attached thereto, and 
 an outlet for an egress from the fuel nozzle of a mixture of the pilot swirler airflow and fuel injected by the pilot fuel injector, the outlet defined by a fuel nozzle outer wall in an outlet end portion of the fuel nozzle, the fuel nozzle outer wall radially spaced apart from the outer boundary wall and defining an airflow passage therebetween, the main fuel injector being arranged within the airflow passage, the fuel nozzle outer wall extending to a radially outermost end of the heat shield to form a cavity for receipt of a flow of air from the airflow passage, the fuel nozzle outer wall defining a radially outer boundary of the cavity, the cavity formed between and defined by the heat shield and an aft end of the main fuel circuit, and the cavity having a greater dimension in a radial direction than in an axial direction; and 
 a main mixer attached to the outlet end portion of the fuel nozzle, the main mixer extending about the outlet radially outward from the fuel nozzle outer wall, the main mixer defining a plurality of main mixer inlet apertures formed on an outer circumference surface of the main mixer for an ingress into the main mixer of a main mixer airflow, the main mixer further defining a main mixer outlet for an egress from the main mixer of a mixture of the main mixer airflow and fuel injected by the main fuel injector into the main mixer, 
 wherein the main fuel injector comprises a main fuel injection port disposed longitudinally aft, with respect to a centerline axis of the fuel nozzle assembly, of an aft end portion of each of the plurality of main mixer inlet apertures, 
 wherein the main fuel injection port is arranged radially inward of the fuel nozzle outer wall extending through the airflow passage and is angled aft with respect to the centerline axis of the fuel nozzle assembly, and is further angled with respect to the radial direction extending from the centerline axis of the fuel nozzle assembly and a circumferential direction extending about the centerline axis of the fuel nozzle assembly, and 
 wherein the fuel nozzle outer wall includes an aperture therethrough aligned with the main fuel injection port. 
 
     
     
       2. The fuel nozzle assembly of  claim 1 , wherein the main fuel circuit is formed using an additive manufacturing process. 
     
     
       3. The fuel nozzle assembly of  claim 1 , wherein the cavity receives the flow of air through apertures defined in the aft end of the main fuel circuit to impinge on a forward surface of the heat shield. 
     
     
       4. The fuel nozzle assembly of  claim 1 , wherein the pilot splitter defines a plurality of apertures about a circumference of the pilot splitter. 
     
     
       5. The fuel nozzle assembly of  claim 1 , wherein the heat shield defines a plurality of heat shield apertures for the flow of air to flow from the cavity to an aft surface of the heat shield for film cooling the aft surface, and
 wherein a first portion of the plurality of heat shield apertures are located closer to an outer radial end of the heat shield than to an inner radial end of the heat shield, and a second portion of the plurality of heat shield apertures are located closer to the inner radial end of the heat shield than to the outer radial end of the heat shield, and 
 the plurality of heat shield apertures are angled to swirl the flow of air provided through the plurality of heat shield apertures. 
 
     
     
       6. The fuel nozzle assembly of  claim 1 , wherein the heat shield defines an aftmost face of the fuel nozzle. 
     
     
       7. The fuel nozzle assembly of  claim 1 , wherein the main mixer outlet is defined forward of the heat shield. 
     
     
       8. A fuel nozzle assembly for a combustor system, comprising:
 a fuel nozzle having: 
 a pilot swirler defining a pilot air inlet for an ingress of a pilot swirler airflow, 
 an outlet for an egress from the fuel nozzle of a mixture of the pilot swirler airflow and fuel, the outlet defined by a fuel nozzle outer wall in an outlet end portion of the fuel nozzle, 
 a main fuel injector, and 
 a pilot fuel injector; 
 a main mixer attached to the outlet end portion of the fuel nozzle, the main mixer extending about the outlet, the main mixer defining a plurality of main mixer inlet apertures formed on an outer circumference surface of the main mixer for an ingress into the main mixer of a main mixer airflow, the main mixer further comprising a main mixer wall spaced radially outward from the fuel nozzle outer wall, the main mixer wall defining a main mixer outlet for an egress from the main mixer of a mixture of the main mixer airflow and fuel; and 
 a main fuel circuit arranged within an airflow passage radially inward of the fuel nozzle outer wall, the main fuel circuit for providing fuel to the main mixer, the main fuel circuit comprising a main fuel injection port disposed longitudinally aft, with respect to a centerline axis of the fuel nozzle assembly, of an aft end portion of each of the plurality of main mixer inlet apertures, 
 wherein the main fuel injection port extends through the airflow passage and is arranged radially inward of the fuel nozzle outer wall and is angled aft with respect to the centerline axis of the fuel nozzle assembly, and is further angled with respect to the radial direction extending from the centerline axis of the fuel nozzle assembly and a circumferential direction extending about the centerline axis of the fuel nozzle assembly, 
 wherein each of the main fuel injector and the pilot fuel injector receives a portion of a fuel flow provided to the fuel nozzle, 
 wherein the main fuel injection port is oriented at a non-perpendicular angle with respect to the centerline axis of the fuel nozzle assembly, and 
 wherein the fuel nozzle outer wall includes an aperture therethrough aligned with the main fuel injection port. 
 
     
     
       9. The fuel nozzle assembly of  claim 8 , wherein the main fuel circuit is formed using an additive manufacturing process. 
     
     
       10. The fuel nozzle assembly of  claim 8 , wherein the pilot splitter defines a plurality of apertures along a circumference of the pilot splitter. 
     
     
       11. The fuel nozzle assembly of  claim 8 ,
 wherein the aperture through the fuel nozzle outer wall is angled downstream with respect to the centerline axis of the fuel nozzle assembly.